What is Stormwater? Where does it come from and where does it go?

In San Joaquin County we get an average of 16 inches of rain each year - which is also called stormwater. Have you ever wondered where all that stormwater goes? In unpaved areas, the water absorbs into the ground, which is beneficial for plants and helps maintain groundwater. However, in developed areas with impervious surfaces such as rooftops, paved roads, driveways, and parking lots, the water is unable to absorb into the ground and instead flows over the impervious surfaces, through gutters, into storm drains, and ultimately into the local waterways.

As this stormwater flows over the urban landscape, it can pick up any substances that it comes into contact with including animal waste, automobile fluids, pesticides, trash, and other pollutants, which find their way into the storm drain system. The storm drain system - which consists of curbs, gutters, and storm drains - carries water untreated into local creeks and rivers.

San Joaquin County is very fortunate to have numerous water resources, including rivers, streams, sloughs, marshes, wetlands, channels, harbors, and underground aquifers. This includes the Sacramento-San Joaquin Delta consisting of the San Joaquin River and its tributaries. These waterways provide a host of benefits, including habitat for wildlife (including the largest striped bass spawning grounds on the Pacific Coast), transportation for commercial ships, and recreational opportunities like boating, swimming, and fishing.

To protect our waterways and the people, fish, birds, and animals that use them, the City of Stockton and County of San Joaquin  have partnered and developed a Stormwater Management Plan (SWMP) that  complies with the Central Valley Region-Wide NPDES Permit. The SWMP identifies the programs and practices that need to be implemented by the City, County, and the residents and businesses to reduce  the pollutants that could get into the storm drainage system and harm our waterways. Although the SWMP addresses a wide range of potential issues, the programs and practices specifically target the following types of  pollutants:

Visit the following pages to learn how YOU can help reduce stormwater pollution in your community and protect our local water resources: